The proposed work will be a continuation of studies of host defense mechanisms against serious bacterial and fungal disease. Emphasis during the coming year will be on studies of neutrophil functions of adhesion chemotaxis, phagocytosis and metabolic response related to microbial killing. These neutrophil functions will be compared to normal controls in patients which are unusually susceptible to infection. Patients with abnormalities of neutrophil chemotaxis are frequently identified and it will be determined if there are serum factors in these patients which react with membrane receptors. Highly sensitive methods for measuring kinetics of phagocytosis and for measuring metabolic responsiveness will be utilized for investigation of cytophilic serum factors. Studies of chemiluminescence will continue to be directed identification of abnormalities of this response in children with recurrent infections or in patients that are subjected to therapies associated with increased susceptibility to infection such as chronic dialysis or bone-marrow transplantation. BIBLIOGRAPHIC REFERENCES: Grebner, J.V., Mills, E.L., Gray, B.H. and Quie, P.G.: Comparison of phagocytic and chemiluminescence response of human polymorphonuclear neutrophils. J. Lab. Clin. Med., 89:153-159, 1977. Peterson, P.K., Verhoef, J. and Quie, P.G.: Influence of temperature on opsonization and phagocytosis of staphylococci. Infect. Immun. 15:175, 1977.